So far the only update I know of that could potentially invalidate a Win7 install is KB971033, which after hidden once goes away forever.
Every single update after that should be able to install without a problem. The actual Windows 7 Update Descriptions in Windows Update aren't bad either, I'm pretty sure Microsoft by law isn't allowed to say "this is a update to fix a bug" and actually have it be another validation checkup. So I would just read the update descriptions as they come along.